The lower cheek on my helmet curves out ward a bit, this disallows the t-visor to sit flush with the helmet. I was thinking of heating it and bending it back inwards. Question is what would be the best way to bend it back and have it stay?
What I did was turn it upside down in the sink and ran hot water in it. This got it soft and flexible. Once it was formed to how I liked it, I ran cold water in and displaced the hot. When it filled with cold, it hardened the plastic back up. You can use a ballon to keep the flare at the bottom afterwards. Just don't set it down on the dome or it will flatten out. Then use the bondo fiberglass sheet and fg mix to line it with.
I ended up boiling the cheek and cooling it in cold water. I was worried if it would break down enough in order for the bend to stay, but it did, it remided me of when I had to boil my mouth gaurds for hockey. Thanks for the help
First I used a heat gun to modify the helmet, after I used cool water to make the plastic goes hard again, and finally I put some fiberglass past (I found it in a shop under this name, in a similar format that the glue but with two components) inside the helmet from the cheeks to the backside keeping the desired shape with a piece of wood, until the fiberglass goes hard. Using sandpaper it will fix better.
Now my helmet has a great shape and it´s strong! I have not pics of the process, sorry.